As Apple sold out of its launch inventory of all iPad mini models, online retailer Amazon made a direct assault on the new 7.9-inch tablet, with a large ad on its front page saying the Kindle Fire HD offers "much more for much less."

Apple marketing chief Phil Schiller has publicly come to the defense of the $329 entry price of the iPad mini, saying he believes customers are willing to pay for quality that rivals like Amazon and Google don't offer.

Amazon on Wednesday asked a federal judge to throw out an ongoing court case Apple leveled against the online retail giant for allegedly misusing the "App Store" name, saying the term has become so widespread that it is now generic.

Amazon's new Kindle Fire HD lineup offers a variety of options at aggressive price points, but Apple's iPad — particularly with the anticipated October launch of a so-called "iPad mini" — is expected to remain the market leader.

Amazon took a direct shot at Apple on Thursday when it unveiled its new Kindle Fire HD 4G LTE, with the same $499 starting price as Apple's current generation iPad. But the main selling point is a new $50-per-year, 250-megabyte-per-month 4G LTE data plan.

Amazon on Thursday announced its new Kindle lineup, led by a 16-gigabyte 8.9-inch Kindle Fire HD priced at $299, along with a $199 7-inch model, an updated $159 Kindle Fire with a faster processor, and a new e-ink frontlit Kindle Paperwhite starting at $119.

Looking to avoid an antitrust suit from the European Union, Apple and four publishers have offered concessions to retailers, including Amazon.com, that would allow them to sell e-books at a discounted rate for two years.

Amazon on Thursday issued a press release boasting that its Kindle Fire has accounted for 22 percent of tablet sales in the U.S., but still did not publicly state exactly how many tablets the company has sold.